The invention relates to the field of oil processing and the petrochemical industry, mainly to installations for vacuum distillation of liquids, such as crude oil for example. It can be used particularly for the rectification of oil stock.
A vacuum-producing unit for crude oil rectification is known, wherein a water steam ejector provides a vacuum in a rectification column (see U.S. Pat. No. 2,680,709, cl. 202-204, 1954).
During operation of this unit vapors of a liquid product mix with the motive water steam. As a result, water condensate with emulsified impurities of oil derivatives is generated. Purification of such waste water from detrimental oil emulsions is a complex technical problem causing significant expenses.
RU patent No. 2048156 (M cl. B 01 D 3/10, 1995) discloses a vacuum unit for the distillation of liquids, which has been chosen by the present inventors as the prototype for the invention. The unit comprises a vacuum rectification column and a vacuum-producing device. The rectification column has a pipeline for feed of a stock product and pipelines for export of a gas-vapor phase and a liquid fraction. The vacuum-producing device is composed of a liquid-gas jet apparatus, a separator and a pump.
In operation of this unit evacuation of the gas-vapor phase from the rectification column is effected by the liquid-gas jet apparatus, which uses the liquid fraction exported from the column as a motive medium. Use of such unit substantially reduces the discharge of waste water with ecologically harmful impurities.
However, the prototype unit has a low efficiency due to the contamination of the motive liquid by oil derivatives and due to the absence of makeup supply of the motive liquid during operation of the vacuum-producing device.